Previously, in the production of allyl acetate through the oxacylation of propylene, acetic acid and oxygen in a vapor phase, a silica carrier impregnated with palladium only was the main catalyst, and alkali or alkaline earth metal compound was used as the activator (U.S. Pat. No. 3,925,452). In order to get better activity from this catalyst, the oxacylation should be performed at higher temperatures. Under these conditions, the formation of carbon dioxide byproduct was increased, and the space time yield (STY, the yield per hour per liter of the catalyst) of allyl acetate was unable to be promoted even by increasing the amounts of palladium or the activator. Generally, by only using palladium as the catalyst during the oxacylation process, the space time yield of allyl acetate would not exceed 60 (g/hr/l of catalyst), and the selectivity of such a catalyst to allyl acetate would only reach 87%. In other words, most of propylene reactant was burned into carbon dioxide or converted into other byproducts. Apparently, when only palladium and the activator were used as the catalyst, the catalytic ability of the catalyst was rather low, and waste resulted from the complete burning of propylene into carbon dioxide, which adversely influenced the industrial process.
In order to improve on this drawback, in the preparation process of the catalyst for oxacylation reaction, other metals were added so as to increase the activity and selectivity of the catalyst (U.S. Pat. No. 3,917,676). Therefore, most of the compositions of the catalysts were comprised of, not only palladium, the main catalyst, and alkali or alkaline earth metal, the activator, but also other metals, as the promoters. For example, along with catalysts with the combination of the main catalyst palladium and the promoters of potassium, bismuth and barium (U.S. Pat. No. 4,571,431), the combination of the main catalyst palladium and the promoters of copper, lead, ruthenium and rhenium (EP 0361484), etc. have been disclosed. Among these, a catalyst with the combination of the main catalyst palladium and the promoter copper exhibited higher activity and selectivity (U.S. Pat. No. 5,011,980).
For the purpose of high catalytic activity and high catalyst selectivity, besides the addition of other metals as the promoter in preparing the catalyst, a certain amount of water as a diluent should be added into the feeding materials of propylene, acetic acid and oxygen for performing the oxacylation reaction, in the traditional process of producing ally acetate. If moisture content was under a certain ratio, the catalytic activity and life of the catalyst could not be retained and would deteriorate rapidly. Usually, the addition of the water diluent would limit the yield of the final product. Further, the final product, allyl acetate, should be purified after the oxacylation, which would result in consuming and wasting energy of the whole process, and the economical effect could not be attained.
In the presence of the catalyst produced in this invention, while no water is added into the reactant materials for the oxacylation process, or only a small amount of water is added in accordance with the requirement of the process, not only will the catalytic activity and life of the catalyst be retained and not deteriorate, but a high catalytic activity and high selectivity will be attained. Therefore, the energy consumed and wasted resulting from the addition of water can be avoided, and the economical effect of the oxacylation process can be greatly increased.